1. Field of the Invention
The present invention concerns a device and method for localization of a tissue variation for a biopsy, and in particular to such a device and method employing x-ray imaging.
2. Description of the Prior Art
The benign or malignant nature of a tissue variation can be determined by means of a tissue sample extraction and subsequent histological examinations. The determination of localizations of tissue variations is based on x-ray images. In order to localize tissue variations, for example in the breast, an overview x-ray exposure of the breast is acquired first. A tissue variation can be localized using the generated overview x-ray exposure. In the continuation of the examination, two additional x-ray exposures are made with different alignments of the x-ray focus relative to the breast. These x-ray exposures are also designated as stereo image exposures. Starting from a vertical alignment of a central ray emanating from an x-ray head, a first x-ray image and a second x-ray image of the breast are produced from different acquisition angles relative to said breast.
It is the goal of a treating physician to determine local sites that belong together in the first x-ray image and in the second x-ray image, which local sites could be used for as a target site for a biopsy (meaning for the extraction of a tissue sample). Since a number of tissue variations can be visible in the x-ray images, however, it is very difficult to determine local sites in the x-ray images that can be biopsied. Additionally, the physician must already decide using the overview image whether a visible abnormality (for example at the border of the x-ray exposure) can be biopsied in the continuation of the examination. In the conventional procedure it may occur that, due to the assessment of a tissue variation that can be biopsied that is situated in the border of the overview image, the breast must be repositioned on the x-ray placement table and a new overview x-ray image produced, even though this local site would have been reachable in a biopsy. It may also occur that a tissue variation at the border region is classified as being able to be biopsied and additional x-ray images have been produced, but no further conclusion in relation to a biopsy capability with regard a specific locality could be derived from these additional images. Such a procedure entails the disadvantages that the duration of the examination is extended by the repositioning and the additional x-ray acquisitions cause the radiation exposure for the patient to be increased.